Formula_20717

\[\begin{gathered}\frac{\partial \rho_{k}}{\partial t}+\operatorname{div} \boldsymbol{J}_{k}=0, \quad \frac{\partial \mu_{k}}{\partial t}+\operatorname{div} \mu_{k} v_{k}=0, \\\boldsymbol{J}_{k}=\rho_{k} v_{k}, \mu_{k} / m_{k}=\rho_{k} / q_{k},\end{gathered}\]